The present invention relates to active elements which are used to control an optical wavefront by altering its phase characteristics. Such elements are useful when it is desired, for example, to precisely adjust an optical path length in order to produce a desired wavefront correction. Among prior art devices, there exist deformable mirror assemblies in which a plurality of discrete piezoelectric actuation devices are attached to a mirror substrate, which may be either a monolithic mirror or a segmented set of mirrors.
To use such a prior art device to control a wavefront, one computes a desired continuous surface contour of a deformable mirror based on a set of performance requirements, and then determines a set of control signals to actuate some of the discrete piezoelectric actuator devices so as to deform the mirror into a shape which approximates the desired surface contour. The smoothness of achievable surface shapes depends in part on the number of actuators and their influence functions. Such deformable mirror systems are complex, expensive, bulky and have severe spatial and temporal bandwidth performance limitations.
Accordingly, it is desirable to provide an improved active mirror assembly.